[Extensive reduction of anti-human leukocyte antigen antibodies after chemotherapy including blinatumomab for B-cell acute lymphoblastic leukemia].

A 66-year-old man with fever was diagnosed with B-cell acute lymphoblastic leukemia. He failed to achieve complete remission after initial hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone (Hyper-CVAD) therapy and was referred to our hospital to undergo allogeneic stem cell transplantation. Bone marrow aspiration showed 97.5% lymphoblasts positive for CD19. Blood tests revealed the presence of broad antihuman leukocyte antigen (HLA) antibodies. After blinatumomab therapy, bone marrow aspiration showed 19.6% blasts. Furthermore, after additional mini-mitoxantrone, etoposide, and cytarabine (mini MEC) therapy, the patient achieved complete remission. Interestingly, after blinatumomab therapy, the blood tests revealed that the titers of anti-HLA antibodies had decreased, and cord blood transplantation was performed in complete remission. This case report revealed that chemotherapy including blinatumomab, which targets CD19-positive cells, has the potential to decrease antibody-producing cells, thus leading to a dramatic reduction of anti-HLA antibodies.